Angle that is smaller than a right angle (less than 90Â°). Angle formed by two lines or two perpendicular planes that measures 90Â°. Symbol denoting that a straight line meets another at a right angle. Symbol denoting that two straight lines do not remain at a constant distance from one other. Symbol denoting that two straight lines remain at a constant distance from one another.
Constriction vs. Dilation. Constriction and dilation are opposite, but related, processes in the body. Whereas dilation is an opening or widening of a structure or passageway to increase material flow, constriction leads to a decrease in material flow by closing the passage.
1 Constriction of the pupil that is excessive, relative to the amount of light the pupil receives. 2  Constriction of the pupil to a diameter of less than two millimeters. 3  Constriction of the pupil with causes including both abnormal and physiological ones.  Pupillary constriction by abnormal causes.